Earlier quoted context omitted.
Your no answers reminds me of an experiment I read about where they determined people were more likely to accept a request if you included pretty much any justification, even when totally self evident. E.g people are more likely to cut in line at the copier if you say 'can I cut in line, because I need to make a copy'. Even with an inane excuse like that (everyone else there also needs to make a copy) people are more…
To be honest I might be at the copy machine to make a copy but I might not actually need to make it then and there. I might be able to re-print it, or do it later. When someone tells me he needs to do that then I think maybe it's more urgent than mine. I wonder if there are subtleties like this that explain these in reality.
For some it is more important, and they won't yield, but some proportion will doing something because the cost of doing it is low enough that there's no reason not to.
In that case giving a reason creates a cost in persisting in that you need to consciously think through whether or not it's worth arguing over, and if so what to respond. And sometimes that is enough that you'll just shift your focus to something else and not bother.
I have no doubt the effectiveness will vary greatly depending on type of action, and that it will vary greatly depending on other factors tied to why people wanted to carry out a given action in the first case, of course, but I also think people ask for or do a lot of things where they have not really made a conscious decision that they need it, just decided on a whim that there's no reason not to ask.
Especially with group dynamics involved, it might have been as simple as someone asking a question in a meeting ("do we need the source?" for example) and someone deciding "might as well ask for it, just in case", with nobody actually caring enough to defend it i you stand up to the demand. In that case the need is low enough that even a totally inane excuse for saying no might stand up even if it on the surface looks like a big, important question.